Differential abscopal effect in extracranial and intracranial lesions after radiotherapy alone for vertebral bone metastasis of unknown primary: a case report

Glasgow prognostic score for assessing the efficacy of whole-brain radiation therapy in cases of recursive partitioning analysis class 2 and class 3 multiple brain metastases: a retrospective study

PURPOSE

Whole-brain radiotherapy (WBRT) may not be beneficial for patients with brain metastases (BMs). The Glasgow Prognostic Score (GPS) is a suggested prognostic factor for malignancies. However, GPS has never been assessed in patients with BMs who have undergone WBRT. The purpose of this study was to determine whether GPS can be used to identify subgroups of patients with BMs who have a poor prognosis, such as recursive partitioning analysis (RPA) Class 2 and Class 3, and who will not receive clinical prognostic benefits from WBRT.

MATERIALS AND METHODS

A total of 180 Japanese patients with BMs were treated with WBRT between May 2008 and October 2015. We examined GPS, age, Karnofsky Performance Status (KPS), RPA, graded prognostic assessment (GPA), number of lesions, tumor size, history of brain surgery, presence of clinical symptoms, and radiation doses.

RESULTS

The overall median survival time (MST) was 6.1 months. seventeen patients (9.4%) were alive more than 2 years after WBRT. In univariate analysis, KPS ≤ 70 (p = 0.0066), GPA class 0-2 (p = 0.0008), > 3 BMs (p = 0.012), > 4 BMs (p = 0.02), patients who received ≥ 3 Gy per fraction (p = 0.0068), GPS ≥ 1 (p = 0.0003), and GPS ≥ 2 (p = 0.0009) were found to significantly decrease the MST. Patients who had brain surgery before WBRT (p = 0.036) had a longer survival. On multivariate analysis, GPS ≥ 1 (p = 0.008) was found to significantly decrease MST.

CONCLUSION

Our results suggest that GPS ≥ 1 indicates a poor prognosis in patients undergoing WBRT for intermediate and poor prognosis BMs.

The abscopal effect: inducing immunogenicity in the treatment of brain metastases secondary to lung cancer and melanoma

PURPOSE

The phenomenon of radiation therapy (RT) causing regression of targeted lesions as well as lesions outside of the radiation field is known as the abscopal effect and is thought to be mediated by immunologic causes. This phenomena has been described following whole brain radiation (WBRT) and stereotactic radiosurgery (SRS) of brain metastasis (BM) in advanced melanoma and non-small-cell lung cancer (NSCLC). We systematically reviewed the available literature to identify which radiation modality and immunotherapy (IT) combination may elicit the abscopal effect, the optimal timing of RT and IT, and potential adverse effects inherent to the combination of RT and IT.

METHODS

Using PRISMA guidelines, a search of PubMed, Medline, and Web of Science was conducted to identify studies demonstrating the abscopal effect during treatment of NSCLC or melanoma with BM.

RESULTS

598 cases of irradiated BM of melanoma or NSCLC in 18 studies met inclusion criteria. The most commonly administered ITs included PD-1 or CTLA-4 immune checkpoint inhibitors (ICI), with RT most commonly administered within 3 months of ICI. Synergy between ICI and RT was described in 16 studies including evidence of higher tumor response within and outside of the irradiated field. In the 12 papers (n = 232 patients) that reported objective response rate (ORR) in patients with BM treated with RT and concurrent systemic IT, the non-weighted mean ORR was 49.4%; in the 5 papers (n = 110 patients) that reported ORR for treatment with RT or IT alone, the non-weighted mean ORR was 27.8%. No studies found evidence of significantly increased toxicity in patients receiving RT and ICI.

CONCLUSION

The combination of RT and ICIs may enhance ICI efficacy and induce more durable responses via the abscopal effect in patients with brain metastases of melanoma or NSCLC.

Abscopal Effect on Bone Metastases from Solid Tumors: A Systematic Review and Retrospective Analysis of Challenge within a Challenge

BACKGROUND

Abscopal effect (AE) describes the ability of radiotherapy (RT) to induce immune-mediated responses in nonirradiated distant metastasis. Bone represents the third most frequent site of metastasis and an immunologically favorable environment for the proliferation of cancer cells. We revised the literature, searching documented cases of AE involving bone metastases (BMs) and evaluated the incidence of AE involving BMs in patients requiring palliative RT on BMs or non-BMs treated at our department.

METHODS

Articles published in the PubMed/MEDLINE database were selected using the following search criteria: ((abscopal effect)) AND ((metastases)). Patients with BMs, who underwent performed bone scintigraphy before and at least 2-3 months after RT, were selected and screened between January 2015 and July 2022. AE was defined as an objective response according to the scan bone index for at least one nonirradiated metastasis at a distance > 10 cm from the irradiated lesion. The primary endpoint was the rate of AE on BMs.

RESULTS

Ten cases experiencing AE of BMs were identified from the literature and eight among our patients.

CONCLUSIONS

The analysis performed here suggests the use of hypofractionated radiotherapy as the only triggering factor for AE of BMs through the activation of the immune response.

Systemic benefit of radiation therapy via abscopal effect

Evidence of a systemic response related to localized radiation therapy (RT) in cancer management is rare. However, enhancing the immune response via immunotherapy followed by localized RT has shown evidence of tumor shrinkage to non-irradiated metastatic disease thereby inducing an "abscopal effect." Combined induction of the cGAS-STING pathway and activation of IFN-gamma signaling cascade related to RT within an activated immune environment promotes neoantigen presentation and expansion of cytotoxic effector cells enabling enhancement of systemic immune response. A proposed mechanism, case examples, and clinical trial evidence of "abscopal effect" benefit are reviewed. Results support strategic therapeutic testing to enhance "abscopal effect."

Towards updated understanding of brain metastasis

Brain metastasis (BM) is a common complication in cancer patients with advanced disease and attributes to treatment failure and final mortality. Currently there are several therapeutic options available; however these are only suitable for limited subpopulation: surgical resection or radiosurgery for cases with a limited number of lesions, targeted therapies for approximately 18% of patients, and immune checkpoint inhibitors with a response rate of 20-30%. Thus, there is a pressing need for development of novel diagnostic and therapeutic options. This overview article aims to provide research advances in disease model, targeted therapy, blood brain barrier (BBB) opening strategies, imaging and its incorporation with artificial intelligence, external radiotherapy, and internal targeted radionuclide theragnostics. Finally, a distinct type of BM, leptomeningeal metastasis is also covered.